Lips are continuously moving and subjected to repeated stress (ultraviolet radiation, dry air, etc.). The lip area is fragile by nature and needs protection in order to overcome the deficiency, or gradual decline of dermal macromolecules. Naturally dry through the fineness of the barrier and absence of moisturizing and lipid restoring glands, the vermilion of the lips is continuously subjected to drying. The mechanisms resulting in moisturization have to be strengthened to limit chapping and cracking. The vermilion of the lips is devoid of sebaceous and sweats glands. Unlike the skin, the lips have no hydrolipid protective film.
Aging of the lip zone is characterized by increased water loss, loss of volume and changes in syntheses which gives rise to a decrease in dermal density. The progressive reduction in collagens accompanied by the fall in collagen I and collagen III levels is largely responsible for the gradual loss of dermal thickness and hence the decrease in lip volume.